class Point{
   int x,y;
   void setXY(int m,int n){
     x =m;
     y = n;
   }
}
public class Example4_4{
   public static void main(String args[]){
     Point p1,p2;
     p1 = new Point();
     p2 = new Point();
     System.out.println("p1的引用 :"+p1);
     System.out.println("p2的引用 :"+p2);
     p1.setXY(1111,2222);
     p2.setXY(-100,-200);
     System.out.println("p1的xy坐标 :"+p1.x+","+p1.y);
     System.out.println("p2的xy坐标 :"+p2.x+","+p2.y);
     p1 = p2;
     System.out.println("将p2的引用赋值给p1后:");
     System.out.println("p1的引用 :"+p1);
     System.out.println("p2的引用 :"+p2);
     System.out.println("p1的xy坐标 :"+p1.x+","+p1.y);
     System.out.println("p2的xy坐标 :"+p2.x+","+p2.y);
   }
}
